Biologists Find New Environmental Threat In North American Lakes

A new and insidious environmental threat has been detected in North American lakes. Boreal forest lakes suffer from 'aquatic osteoporosis.'

Share:

Total shares:

FULL STORY

Water flea, Daphnia, is known to be a key component of many aquatic foodwebs.

Credit: Shelley Arnott

Water flea, Daphnia, is known to be a key component of many aquatic foodwebs.

Credit: Shelley Arnott

A new and insidious environmental threat has been detected in North American lakes by researchers from Queen's and York universities.

Along with scientists from several Canadian government laboratories, the team has documented biological damage caused by declining levels of calcium in many temperate, soft-water lakes.

Calling the phenomenon "aquatic osteoporosis," Queen's PhD candidate Adam Jeziorski, lead author of the study, notes that calcium is an essential nutrient for many lake-dwelling organisms. "Once calcium declines below a certain threshold, some keystone species can no longer reproduce," he says. "These species and other organisms that feed on them are endangered."

The study is published November 27 in the journal Science.

The researchers examined a water flea, Daphnia, known to be a key component of many aquatic foodwebs. Having identified the calcium levels that would damage Daphnia in a laboratory setting, they worked with government scientists to assemble hundreds of "water quality time series" from across the province, explains Biology professor Norman Yan from York University, the Canadian research lead on the threat to aquatic life of calcium decline. "Our hope was to determine if damage was already occurring at key sites, and then see how common these conditions were across the province," he says.

However, calcium decline occurred in many lakes before people knew about the problem and monitoring programs had been put in place. By studying tiny fossils and other indicators in sediment accumulated at the bottom of each lake, Queen's paleoecologist professor John Smol, Canada Research Chair in Environmental Change, and his colleagues were able to reconstruct environmental trends over the past 200 years. The researchers found that key invertebrate species were disappearing in the lakes with declining calcium levels, often starting in the 1970s.

Linking the problem to the long-term effects of acid rain on forest soils, as well as to logging and forest re-growth, the researchers note that, despite signs of chemical recovery from recent reductions in sulphur dioxide emissions, lower calcium levels may delay the biological recovery of lakes from acidification. "This has important management implications," says team member Dr. Andrew Paterson of the Ontario Ministry of the Environment and adjunct professor at Queen's University. "It was a combination of experimental work, paleoecological research and long-term monitoring that helped to identify this emerging threat," he adds.

The authors conclude that the phenomenon of calcium decline is causing widespread transformation of aquatic food webs in boreal lakes in North America, and in other acid-sensitive regions of the globe. While their work focuses on the water flea Daphnia, they note that all life in lakes requires calcium, and many creatures including crayfish, mollusks and fish have quite high calcium demands. They are all at risk, say the researchers, but we don't yet know if calcium levels have fallen to the point of damage.

"This is all very worrisome," concludes Dr. Smol, recipient of the 2004 NSERC Herzberg Gold Medal as Canada's top scientist and co-director of Queen's Paleoecological Environmental Assessment and Research Laboratory (PEARL). "The good news is that we have found the 'miner's canary' in the form of these water fleas that track the decline in calcium levels. The bad news is that many lakes have already passed these critical thresholds."

The research was supported primarily by grants from the Natural Sciences and Engineering Research Council of Canada, as well as funding from the Ontario Ministry of the Environment, Environment Canada and Fisheries and Oceans Canada.

Queen's University. (2008, November 28). Biologists Find New Environmental Threat In North American Lakes. ScienceDaily. Retrieved August 2, 2015 from www.sciencedaily.com/releases/2008/11/081127145141.htm

July 31, 2015  Resettlement projects in the Amazon are driving severe tropical deforestation, according to new research. Widely hailed as a socially responsible and 'innocuous' strategy of land redistribution, ... read more

July 31, 2015  The humble butterfly could hold the key to unlocking new techniques to make solar energy cheaper and more efficient, pioneering new research has shown. By mimicking the v-shaped posture adopted by ... read more

July 30, 2015  China needs to reduce its dependence on coal and improve the range of fuels it uses if it is to have long term energy security, according to new research. The study looks at the future of electricity ... read more

July 30, 2015  North of the Aleutian Islands, submarine canyons in the cold waters of the eastern Bering Sea contain a highly productive 'green belt' that is home to deep-water corals as ... read more

July 30, 2015  New findings have implications for questions regarding how animals and plants grow minerals into shapes that have no relation to their original crystal symmetry, and why some ... read more

July 30, 2015  A new study addresses an important question in climate science: how accurate are climate model projections? Climate models are used to estimate future global warming, and their accuracy can be ... read more

Apr. 9, 2015  Lake and highway authorities should consider adjusting road salt use protocols to protect aquatic life such as the water flea, by taking the nutritional status of the lakes into account, experts ... read more

Nov. 19, 2014  A plague of “aquatic osteoporosis” is spreading throughout many North American soft-water lakes due to declining calcium levels in the water and hindering the survival of some organisms. The ... read more

June 6, 2013  Global warming impacts lakes' structure, function and water quality. Increases in temperature as a result of climate change are mirrored in lake waters where temperatures are also on the rise. A ... read more